Method for preparing sulfate reducing bacteria (SRB) microbial inoculum by using metal organic framework (MOF)

Abstract

The invention discloses a method for preparing a sulfate reducing bacteria (SRB) microbial inoculum by using a metal organic framework (MOF). According to the method, the MOF is used as a fixing carrier for fixing the SRB, so that the rate and the acid resistance of the SRB for treating the acidic sulfate wastewater can be effectively improved. The method provided by the invention is high in treatment efficiency and low in cost, can relieve the acid stress when the acidic sulfate wastewater is treated by the SRB, and is an immobilization method which is high in efficiency, easy to operate and free of pollution.

Description

Technical Field

[0001] The invention belongs to the field of wastewater treatment and microbial immobilization, and relates to a method for preparing an SRB bacterial agent, specifically a method for preparing an SRB bacterial agent by using MOF as a carrier of SRB. Background Art

[0002] During mining exploration and mining, acidic sulfate wastewater with strong acidity, high salt concentration and high dissolved metal concentration is generated due to the exposure of sulfur-bearing strata to the air. High-concentration sulfate wastewater can cause a series of serious environmental problems, leading to water mineralization, metal corrosion, scaling of pipelines and equipment, release of toxic hydrogen sulfide and disruption of the balance of the natural sulfur cycle. Sulfate is easily converted into sulfide, which can combine with hydrogen to form hydrogen sulfide, or combine with metals to form metal sulfide precipitation. If the water containing sulfate is not well treated, the hydrogen sulfide or metal sulfide formed by the sulfate reduction process may have an adverse effect on the environment. The potential hazards of high-concentration sulfate wastewater are extremely difficult to treat and last for a long time. Therefore, controlling the excessive discharge of high-concentration sulfate has become one of the world's largest environmental problems.

[0003] Wastewater containing sulfate is usually treated using physical, chemical and biological technologies. Anaerobic biological technology is also considered one of the most energy-saving and economical technologies. Compared with traditional desulfurization processes, anaerobic acid-producing bacteria and SRB acid-producing desulfurization processes have the advantages of low power consumption, high treatment potential, good stability and high adsorption capacity. However, the growth of SRB is affected by temperature, pH, COD, heavy metals and SO4 2- Affected by factors such as concentration, the pH of acidic sulfate wastewater is generally less than 5, which is not suitable for the growth and metabolism of SRB, greatly limiting the application of SRB in the treatment of acidic sulfate wastewater. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the above-mentioned prior art, provide a method for preparing an SRB bacterial agent that is easy to operate, and improve the rate and acid resistance of SRB in treating acidic sulfate wastewater.

[0005] To achieve the above object, the technical solution of the present invention is as follows:

[0006] A method for preparing SRB bacterial agent using MOF, characterized by comprising the following steps:

[0007] 1. Place Postgate C medium dissolved in distilled water in a sealed anaerobic bottle, adjust the pH to 7.0-7.2, blow nitrogen for 15 minutes, and sterilize at 121°C for 20 minutes;

[0008] 2. After the culture medium has cooled to room temperature, add MOF and 20% SRB bacterial solution to the culture medium and place it in a 35°C constant temperature incubator for static culture;

[0009] 3. After culturing for 3 days, the mixture was centrifuged at 8000r / min for 5 minutes; the solid after centrifugation was washed three times with sterile saline to obtain the MOF-fixed bacteria MOF-SRB;

[0010] 4. Mix MOF-SRB and fresh Postgate C medium and store in a 4°C refrigerator.

[0011] The components of the Postgate C culture medium in step 1 are: KH2PO4 (0.5g / L), MgSO4·7H2O (1.5g / L), Na2SO4 (1.2g / L), CaCl2 (0.06g / L), Fe(NH4)2·(SO4)2·6H2O (0.3g / L), NaCl (1.0g / L), NH4Cl (1.0g / L), sodium lactate (3.5ml / L), yeast powder (1.0g / L), L-cysteine ​​(0.3g / L), and ascorbic acid (0.3g / L).

[0012] The amount of MOF added in step 2 is: 0.6 g / L.

[0013] In the step 2, the MOF is fixed to SRB by adding it to the Postgate C culture medium at the same time.

[0014] In the step 3, the time for fixing SRB with MOF is 3 days, the centrifugal speed for obtaining MOF-SRB is 8000 r / min, and the centrifugal time is 5 minutes.

[0015] The MOF-SRB in step 4 was stored in a refrigerator at 4°C.

[0016] The beneficial effects of the present invention are:

[0017] (1) The MOF used in the present invention has a small particle size, a large specific surface area, and a high reaction activity, and can attach high concentrations of SRB to promote the metabolism of SRB;

[0018] (2) The present invention can not only effectively improve the rate of SRB in treating acidic sulfate wastewater, but also improve the acid resistance of SRB. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 : pH of AMD with different pH values ​​after being treated with MOF-SRB and SRB bacterial solution for 72 h;

[0020] Figure 2: Sulfate content of AMD with different pH values ​​after being treated with MOF-SRB and SRB bacterial solution for 72 h. DETAILED DESCRIPTION

[0021] The present invention will be further described below in conjunction with embodiments:

[0022] A method for preparing SRB bacterial agent using MOF, the steps of which are:

[0023] (1) Place Postgate C medium dissolved in distilled water in a sealed anaerobic bottle, adjust the pH to 7.0-7.2, blow nitrogen for 15 min, and sterilize at 121°C for 20 min;

[0024] (2) After the culture medium has cooled to room temperature, MOF and 20% SRB bacterial solution are added to the culture medium and placed in a 35°C constant temperature incubator for static culture;

[0025] (3) After culturing for 3 days, the mixture was centrifuged at 8000 r / min for 5 min; the solid after centrifugation was washed three times with sterile saline to obtain the MOF-immobilized bacteria MOF-SRB;

[0026] (4) preparing a culture medium with a pH gradient of 5.5, 5.0, 4.5, and 4.0, with the corresponding divalent iron ion content being 50 mg / L, 75 mg / L, 100 mg / L, and 125 mg / L, respectively, and packaging the culture medium in 100 ml anaerobic bottles, passing nitrogen gas, sterilizing, and cooling for later use;

[0027] (5) MOF-SRB and SRB bacterial suspensions were inoculated into the culture medium at the same biomass and at an inoculum rate of 10%. 2 ml of liquid was extracted from each anaerobic bottle at 0 h, 24 h, 48 h, and 72 h, and filtered using a 0.45 μm polyethersulfone filter membrane;

[0028] (6) Determine the pH and sulfate content in each bottle. Figure 1 and attached Figure 2 shown.

[0029] By the attached Figure 1 It can be seen that 3 days after the addition of MOF-SRB, the pH of the anaerobic bottles with pH values ​​of 5.5, 5.0, and 4.5 increased significantly; 3 days after the addition of the bacterial solution, the pH in each anaerobic bottle did not increase significantly.

[0030] By the attached Figure 2 It can be seen that 3 days after the addition of MOF-SRB, the sulfate content in the anaerobic bottles with pH values ​​of 5.5, 5.0, and 4.5 decreased significantly; 3 days after the addition of the bacterial solution, the sulfate content in each anaerobic bottle did not decrease significantly.

[0031] By the attached Figure 1 and attached Figure 2 It can be seen that MOF-SRB significantly improved the rate and acid resistance of SRB in treating acidic sulfate wastewater.

Claims

1. A method for preparing a sulfate-reducing bacteria (SRB) agent using a metal organic framework (MOF), characterized by comprising the following steps:

1. Place Postgate C medium dissolved in distilled water in a sealed anaerobic bottle, adjust the pH to 7.0-7.2, blow nitrogen for 15 minutes, and sterilize at 121°C for 20 minutes; 2. After the culture medium has cooled to room temperature, add MOF and 20% SRB bacterial solution to the culture medium and place it in a 35°C constant temperature incubator for static culture; 3. After culturing for 3 days, the mixture was centrifuged at 8000r / min for 5 minutes; the solid after centrifugation was washed three times with sterile saline to obtain the MOF-fixed bacteria MOF-SRB; 4. Mix MOF-SRB and fresh Postgate C medium and store in a 4°C refrigerator.

2. A method for preparing SRB bacterial agent using MOF according to claim 1, characterized in that: The components of the Postgate C culture medium in step 1 are: KH2PO4 (0.5g / L), MgSO4·7H2O (1.5g / L), Na2SO4 (1.2g / L), CaCl2 (0.06g / L), Fe(NH4)2·(SO4)2·6H2O (0.3g / L), NaCl (1.0g / L), NH4Cl (1.0g / L), sodium lactate (3.5ml / L), yeast powder (1.0g / L), L-cysteine ​​(0.3g / L), and ascorbic acid (0.3g / L).

3. The method for preparing SRB bacterial agent using MOF according to claim 1, characterized in that: The amount of MOF input in step 2 is: 0.6 g / L.

4. The method for preparing SRB bacterial agent using MOF according to claim 1, characterized in that: In the step 2, the MOF is fixed to SRB by adding it to the Postgate C culture medium at the same time.

5. The method for preparing SRB bacterial agent using MOF according to claim 1, characterized in that: In the step 3, the time for fixing SRB with MOF is 3 days, the centrifugal speed for obtaining MOF-SRB is 8000 r / min, and the centrifugal time is 5 minutes.

6. The method for preparing SRB bacterial agent using MOF according to claim 1, characterized in that: The MOF-SRB in step 4 was stored in a refrigerator at 4°C.

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